1. Field of the Invention
This invention relates to ring binders, in particular ring binders having a plurality of openable rings for holding leaves of paper or pages thereon.
In a conventional ring binder, a plurality of rings are flexibly held in alignment on an inside spine portion of a tri-fold cover. The rings are in a circular shape and spreadable from a top junction for threading or inserting the pages thereon. A drawback to this configuration is that threading of the pages thereon must be accomplished with a swinging or rotational displacement of the pages to thread around the curvature of the open half ring. In a conventional D ring binder the substantially straight portion of the "D" has its upper end portion gradually curved to meet the distal end of the arcuate half of the ring. The horizontal profile of the conventional D ring binder is still too great for vertical loading of conventionally punched pages which usually have 5/16" diameter punched holes. Therefore, even with a conventional D, some pivoting of the pages is required for loading.
In photo album manufacture, the albums are shipped with magnetic pages already installed. When installing pages at the factory, operators must accomplish this task manually and because of the movement of their wrists, operators have experienced wrist and arm problems, particularly with carpal tunnel. Machine threading of the pages onto open circular rings is also made more complicated because of the curvature of the rings.